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https://github.com/google/leveldb.git
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36a5f8ed7f
- Replace raw slice comparison with a call to user comparator. Added test for custom comparators. - Fix end of namespace comments. - Fixed bug in picking inputs for a level-0 compaction. When finding overlapping files, the covered range may expand as files are added to the input set. We now correctly expand the range when this happens instead of continuing to use the old range. For example, suppose L0 contains files with the following ranges: F1: a .. d F2: c .. g F3: f .. j and the initial compaction target is F3. We used to search for range f..j which yielded {F2,F3}. However we now expand the range as soon as another file is added. In this case, when F2 is added, we expand the range to c..j and restart the search. That picks up file F1 as well. This change fixes a bug related to deleted keys showing up incorrectly after a compaction as described in Issue 44. (Sync with upstream @25072954)
176 lines
5.2 KiB
C++
176 lines
5.2 KiB
C++
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "leveldb/table.h"
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#include "leveldb/cache.h"
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#include "leveldb/env.h"
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#include "table/block.h"
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#include "table/format.h"
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#include "table/two_level_iterator.h"
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#include "util/coding.h"
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namespace leveldb {
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struct Table::Rep {
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~Rep() {
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delete index_block;
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}
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Options options;
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Status status;
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RandomAccessFile* file;
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uint64_t cache_id;
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BlockHandle metaindex_handle; // Handle to metaindex_block: saved from footer
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Block* index_block;
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};
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Status Table::Open(const Options& options,
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RandomAccessFile* file,
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uint64_t size,
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Table** table) {
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*table = NULL;
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if (size < Footer::kEncodedLength) {
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return Status::InvalidArgument("file is too short to be an sstable");
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}
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char footer_space[Footer::kEncodedLength];
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Slice footer_input;
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Status s = file->Read(size - Footer::kEncodedLength, Footer::kEncodedLength,
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&footer_input, footer_space);
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if (!s.ok()) return s;
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Footer footer;
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s = footer.DecodeFrom(&footer_input);
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if (!s.ok()) return s;
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// Read the index block
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Block* index_block = NULL;
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if (s.ok()) {
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s = ReadBlock(file, ReadOptions(), footer.index_handle(), &index_block);
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}
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if (s.ok()) {
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// We've successfully read the footer and the index block: we're
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// ready to serve requests.
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Rep* rep = new Table::Rep;
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rep->options = options;
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rep->file = file;
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rep->metaindex_handle = footer.metaindex_handle();
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rep->index_block = index_block;
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rep->cache_id = (options.block_cache ? options.block_cache->NewId() : 0);
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*table = new Table(rep);
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} else {
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if (index_block) delete index_block;
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}
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return s;
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}
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Table::~Table() {
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delete rep_;
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}
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static void DeleteBlock(void* arg, void* ignored) {
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delete reinterpret_cast<Block*>(arg);
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}
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static void DeleteCachedBlock(const Slice& key, void* value) {
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Block* block = reinterpret_cast<Block*>(value);
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delete block;
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}
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static void ReleaseBlock(void* arg, void* h) {
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Cache* cache = reinterpret_cast<Cache*>(arg);
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Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
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cache->Release(handle);
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}
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// Convert an index iterator value (i.e., an encoded BlockHandle)
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// into an iterator over the contents of the corresponding block.
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Iterator* Table::BlockReader(void* arg,
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const ReadOptions& options,
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const Slice& index_value) {
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Table* table = reinterpret_cast<Table*>(arg);
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Cache* block_cache = table->rep_->options.block_cache;
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Block* block = NULL;
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Cache::Handle* cache_handle = NULL;
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BlockHandle handle;
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Slice input = index_value;
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Status s = handle.DecodeFrom(&input);
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// We intentionally allow extra stuff in index_value so that we
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// can add more features in the future.
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if (s.ok()) {
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if (block_cache != NULL) {
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char cache_key_buffer[16];
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EncodeFixed64(cache_key_buffer, table->rep_->cache_id);
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EncodeFixed64(cache_key_buffer+8, handle.offset());
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Slice key(cache_key_buffer, sizeof(cache_key_buffer));
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cache_handle = block_cache->Lookup(key);
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if (cache_handle != NULL) {
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block = reinterpret_cast<Block*>(block_cache->Value(cache_handle));
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} else {
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s = ReadBlock(table->rep_->file, options, handle, &block);
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if (s.ok() && options.fill_cache) {
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cache_handle = block_cache->Insert(
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key, block, block->size(), &DeleteCachedBlock);
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}
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}
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} else {
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s = ReadBlock(table->rep_->file, options, handle, &block);
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}
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}
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Iterator* iter;
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if (block != NULL) {
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iter = block->NewIterator(table->rep_->options.comparator);
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if (cache_handle == NULL) {
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iter->RegisterCleanup(&DeleteBlock, block, NULL);
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} else {
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iter->RegisterCleanup(&ReleaseBlock, block_cache, cache_handle);
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}
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} else {
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iter = NewErrorIterator(s);
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}
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return iter;
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}
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Iterator* Table::NewIterator(const ReadOptions& options) const {
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return NewTwoLevelIterator(
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rep_->index_block->NewIterator(rep_->options.comparator),
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&Table::BlockReader, const_cast<Table*>(this), options);
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}
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uint64_t Table::ApproximateOffsetOf(const Slice& key) const {
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Iterator* index_iter =
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rep_->index_block->NewIterator(rep_->options.comparator);
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index_iter->Seek(key);
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uint64_t result;
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if (index_iter->Valid()) {
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BlockHandle handle;
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Slice input = index_iter->value();
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Status s = handle.DecodeFrom(&input);
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if (s.ok()) {
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result = handle.offset();
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} else {
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// Strange: we can't decode the block handle in the index block.
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// We'll just return the offset of the metaindex block, which is
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// close to the whole file size for this case.
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result = rep_->metaindex_handle.offset();
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}
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} else {
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// key is past the last key in the file. Approximate the offset
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// by returning the offset of the metaindex block (which is
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// right near the end of the file).
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result = rep_->metaindex_handle.offset();
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}
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delete index_iter;
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return result;
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}
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} // namespace leveldb
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